The introduction of bioequivalent Allergy Units based on the Intradermal Dilution for 50 mm sum of Erythema determines the Allergy unit (ID50EAL) method provides clinicians with a common unit for diagnosing and treating patients regardless of allergen source. Knowledge of the number of Allergy Units in a standardized extract permits selection of doses for puncture and intradermal testing which are likely to produce equivalent allergic responses. Similarly, doses in Allergy Units for immunotherapy can be selected so that safe initiating doses and safe treatment doses can be selected regardless of source. Using Bioequivalent Allergy Units also facilitates cost comparison among extracts at equal units.